Just in case someone's doing a Search and comes across this (admittedly older) thread, here's some additional info. Hope it'll help someone:
I have an 11/85 Mark III, no stripe I suppose, schematic from 1985.
The Master (Pull Deep) pot is given with a value of 100K on the schematic. They probably don't make the exact original pot anymore. Some time ago Boogie sent me a replacement pot, which looks different. Part #: 596821. I've seen it on eBay, too, where it said it's 250K. I'm measuring what perhaps looks more like 200K. (It's on an older analog Multitester, so who knows...)
If you get this or any other similar pot, you have to make sure it has an Audio Taper (and not Linear Taper), otherwise it'll jump from zero to full-on with just a tiny turn.
It seems it's next to impossible to find a 100K pot, Audio Taper, WITH Push/Pull anymore. That's probably why Boogie sent me this one (596821) with ~200K instead.
I was able to locate locally a couple completely different replacement pots in the past, and with the need for Audio Taper I was able to find (and use) both 100K and 250K, but without a push/pull function. So I just had the wiring permanently set for "Deep."
The 100K ramps up perhaps a little more gradually with lower settings than the 250K.
Seeing that most schematics for the Mark III available online seem kinda hard to make out I'll try to scan mine, and maybe I'll try to approach
http://tubefreak.com/tubefreak.html
to see if he can display it along with the other schematics he has.
We'll see.
Hope this helps.